1. Field of the Invention
The present invention relates to a fuel tank installed in an automobile or other vehicle and, more particularly, to a vehicular fuel tank capable of preventing escape of fuel vapors into the atmosphere when fuel is being supplied into the tank.
2. Description of the Prior Art
For the conventional fuel tank of this kind, when the amount of the fuel remaining in the tank becomes small, the space above the fuel level is permeated with a large amount of fuel vapor. Therefore, the fuel tank is required to prevent the escape of the fuel vapors into the atmosphere when fuel is being supplied into the tank.
In order to satisfy this requirement, the conventional fuel tank is provided with a communication passage that is in communication with the charcoal canister. This passage is opened when the filler lid or filler cap is opened. In this structure, the fuel vapors can be guided into the canister by opening the cover member such as the filler lid.
In some fuel tanks the aforementioned communication passage is opened when the filler lid is taken off. A fuel tank described in Japanese Utility Model Laid-Open No. 119420/1988 utilizes a solenoid valve. Another fuel tank described in U.S. Pat. No. 4,659,346 makes use of a wire.
Where the solenoid valve is used, the cost is increased. Where the wire is employed, it is necessary that the shaft of the valve connected to the front end of the wire have a seal for isolating the inside of the tank from the atmosphere. In this structure, therefore, the seal is worn away by movement of movable members such as the wire. Hence, the lifetime of the seal is shortened. This leads to a deterioration in the reliability of the fuel tank.
A further known fuel tank in which the communication passage is opened when the filler cap is taken off uses a control valve for opening and closing the passage. This control valve which makes use of a coil spring to mechanically open and close the passage is mounted in the filler tube, as described in U.S. Pat. No. 4,651,889.
This control valve makes direct contact with the filler cap inside the filler tube and moves with the cap. This necessitates a seal around the control valve to isolate the inside of the tank from the atmosphere. Since this seal is kept in contact with the moving control valve, the seal is worn away. Consequently, the reliability including the life is poor.